1. Field of the Invention
The present invention relates to an electromechanical actuator provided with an electric motor, a power transmission mechanism that has a nut portion and a screw portion and converts driving force in a rotational direction into driving force in a linear direction and transmitting the driving force, and an output portion that is displaced in a linear direction and outputs the driving force, and an electromechanical-actuator power disconnection method and an electromechanical-actuator power disconnection apparatus for breaking connection of a driving force transmission path in the electromechanical actuator and disconnecting transmission of power.
2. Description of the Related Art
Conventionally, electromechanical actuators for driving various kinds of equipment by being displaced to extend and contract along a linear direction are used as actuators for driving equipment in various fields such as, for example, aircrafts. Such an electromechanical actuator is provided with an electric motor, a power transmission mechanism that has a nut portion and a screw portion and converts driving force in a rotational direction into driving force in a linear direction and transmitting the driving force, and an output portion that is displaced in a linear direction and outputs the driving force. With such an electromechanical actuator, a jammed state may occur in the above-mentioned power transmission mechanism due to tortion, seizure, or the like.
To prepare for occurrence of the above-mentioned jammed state, it is important for electromechanical actuators to be able to maintain reliability of operation of equipment to be driven as a result of the electromechanical actuators being capable of shifting, in the case of occurrence of the jammed state, to a state where the equipment to be driven can operate. For example, in the case where equipment is driven by an actuator other than an electromechanical actuator in which the jammed state occurs, the electromechanical actuator is provided with a structure that enables this electromechanical actuator to follow operation of the other actuator without impeding the operation of the other actuator, thereby maintaining the reliability of the operation of the equipment.
U.S. Pat. No. 5,214,972 discloses an electromechanical actuator provided with a first actuator and a second actuator so as to extend in opposite directions on the same axis. In this electromechanical actuator, each of the first and second actuators is provided with a power transmission mechanism serving as a ball screw mechanism, and an electric motor. With this configuration, even if the jammed state occurs in the power transmission mechanism in one of the first and second actuators, the electromechanical actuator can shift to a state where the equipment to be driven can operate. In other words, when the jammed state has occurred in one of the first and second actuators, the equipment to be driven can operate by the other actuator provided so as to extend on the same axis as, and in the direction opposite to, the actuator in which the jammed state has occurred.
US Patent Application Publication No. 2005/0103928 discloses the second embodiment of an electromechanical actuator provided with an electric motor serving as a driving power source, an output portion, a power transmission mechanism serving as a ball screw mechanism, and a power disconnection mechanism capable of breaking connection of a driving force transmission path between the power transmission mechanism and the output portion and disconnecting transmission of power. The above-mentioned power disconnection mechanism in this electromechanical actuator is configured as an electromechanical clutch mechanism capable of breaking connection between a nut portion in the power transmission mechanism and the output portion.
The electromechanical clutch mechanism is provided with a clutch-driving electric motor that is separate from the above-mentioned electric motor serving as the driving power source. This electromechanical clutch mechanism is further provided with mechanisms such as a gear mechanism for transmitting driving force of the clutch-driving electric motor, and a locking plate that is provided among the gear mechanism, the nut portion, and the output portion, and has a mesh structure and an engagement structure therefor.